transformer controlling h-bridge?

Thread Starter


Joined Sep 21, 2011
I salvaged some circuit boards from discarded equipment (a Dukane Ultrasonic Generator). It has 4 transistors on a heat sink in an H-bridge configuration, and the driver board has a transformer at the heart of it (labeled U1 in the attachment). The transformer has 10 leads: 3 and 8 are grounded, 5 and 6 connect to control wires from another board, 2 and 9 connect to the load (unknown on another board), and the remaining leads connect to the base resistors for the H-bridge.
I want to understand how this works and maybe use it in a project, but I don't know what the transformer is doing. All my search results showed a transformer as the load of the bridge, but not on the control side.
Any ideas or links to similar circuits would be greatly appreciated.